1979 450 SEL Starting Problems
 

My 1979 450 SEL 4.5 litre engine has two problems.
1. After the car has run for awhile and comes up to temperature, once it is turn off it does not always want to start again. At times I have to let it sit for a least half an hour. Any suggestions?
2. Recently during the warmer weather with A/C running the idle will drop below 500RPM'S and sometimes it quits running. Then the number one problem kicks in. Very hard to enjoy this vehicle when it is running like this. Need help.
Note: I own six older MB'S.